The rate of sexually transmitted diseases in people over 45 doubled over the last decade, researchers found by checking reports from 19 sexual health clinics.

In 1996, the overall infection rate was 16.7 per 100,000 people in that age group. By 2003, it had risen to 36.3 per 100,000 researchers said.

They found 4,445 infections among people over 45 during that time. Most were in straight people, according to a news release.

Nearly half of the cases were genital warts, and herpes was next common, making up about 20 percent of cases. Cases of chlamydia, herpes, gonorrhea and syphilis all rose as well.

Among women, the rates were highest among those aged 45 to 54; among men, rates were highest among those aged 55 to 60 plus.

The authors of the study, which appeared in the journal Sexually Transmitted Infections, said that programs should be aimed at preventing STDs in age groups other than young people.

The study was conducted in the United Kingdom.